Commercially-available polyurethane foams, elastomers and aqueous polyurethane dispersions currently are generally produced using polyether diols, polyols derived from polymerization of ethylene oxide and propylene oxide, polyester polyols, vegetable oil-based polyols, and blends of two or more thereof. The majority of the polyurethanes are prepared from petroleum based feedstocks. While the polyurethane foams prepared using these raw materials exhibit useful properties, they suffer from the fact that the starting materials are petroleum based and not available from renewable sources.
U.S. Pat. No. 6,946,539, US2007/0129524A1, US2009/0124719A1, and US2008/0039582A1, disclose polyurethanes prepared using a poly(trimethylene ether)glycol. Poly(trimethylene ether)glycol (PO3G) is readily prepared by polycondensation of 1,3-propanediol (and optionally other glycols such as ethylene glycol) which, as previously disclosed in U.S. Pat. No. 5,633,362, U.S. Pat. No. 5,686,276 and U.S. Pat. No. 5,821,092, can be prepared by a fermentation process using a renewable biological source. The disclosed renewably sourced PO3G polymers are linear polyether glycols having a number average hydroxyl functionality of about 2 or slightly less than 2 due to the presence of low unsaturated end groups. The lack of high hydroxyl functionality renders the renewable sourced poly(trimethylene ether)glycols of limited use in polyurethane foams.
Natural oil polyols (NOPs) having high hydroxyl functionality have been used to replace petrochemical based polyols in production of polyurethane rigid and flexible foams. However, making flexible polyurethane foams from the NOPs having a renewable content more than about 50%, and less than about 50% petroleum based content, and having desirable performance characteristics can be challenging because of their chemistry and properties relative to conventional polyether polyols. For example, NOPs generally have less-reactive sterically hindered secondary hydroxyl groups, unsaturation, greater hydrophobicity as compared to conventional oils, and can have inconsistencies in composition. Foams made from NOPs can be less flexible and/or less resilient than conventional flexible polyurethane foams.
A renewably sourced polyol having hydroxyl functionality greater than two, with low freezing point and having a good balance between hydrophilic and hydrophobic character would have benefits in production of products such as foams, polyurethane themosets, coatings, adhesives and sealants with excellent properties, as well as many other end uses.